On Sun, 14 Dec 2003 22:08:14 GMT, "Larry Silkaitis"
<
[email protected]> may have said:
>
>
><"Werehatrack" <
[email protected]> wrote in message
><
news:[email protected]...
>> On Sun, 14 Dec 2003 18:13:09 GMT, Werehatrack <
[email protected]> thus amends himself:
>>
>> >On Sun, 14 Dec 2003 11:13:01 -0000, "Pete Biggs" <pbiggmellon{remove_fruit}
[email protected]>
>> >wrote:
>> >
>> >>
[email protected] wrote:
>> >>> First: It is not true that the common patches vulcanize. If you want to try it, just heat a
>> >>> patched tube by pressing the patch against a fairly hot Teflon coated frying pan. This is the
>> >>> best method of pulling off an old REMA patch. Vulcanized patches do not come off.
>> >>
>> >>That's dissappointing. My Velox patches that appeared to be vulcanizded have failed the frying
>> >>pan test. Still, they normally stick and stay stuck very well.
>> >>
>> >>Why is cement sometimes called "vulcanizing rubber solution"?
>> >
>> >Because the people designing the labels and choosing the terminology do not understand the
>> >product.
>>
>> As pertains to patching a tube or a tire...
>>
>> >Vulcanizing is, specifically and solely, a heat-bonding process that melts one of the two
>> >substances in order to bond the two together, like a solder joint in metal. Some solvent-based
>> >cements are supposed to schieve something similar to this by a solvent weld, but in my
>> >experience, it doesn't occur most of the time. The adhesive that is carried in the cement's
>> >solvent is what ends up doing the bonding, from what I've seen.
>>
>> (Vulcanizing more generally applies to heating the rubber to melt, form and cure it.)
>
>Vulcanizing is NOT melting. It is a chemical reaction. Natural rubber (from trees) is cured by
>sulfur and heat. The old patched required lighting the patch and applying and clamping it to
>the tube.
It's in molten form during at least some part of the process if I recall correctly. The heat level
needed produces that effect. Afterwards, if memory serves, the temp for remelting it is higher.
Since synthetic rubber is a different matter, though, the whole "vulcanizing" term is really not
applicable to modern products. My recollection is that the old vulcanizing patches were both cured
and fused by the heat, but I know that the last few times I tried to use one during the '60s, they
didn't bond worth a damn. The people at the parts stores advised switching to cold patches. I think
the bottom line is that the hot patches only worked with the old tubes. As such, "vulcanizing" is
*really* an obsolete concept.
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